Conventional stereo recordings can capture acoustic images from a horizontal arc of up to 180 degrees, which I believe is known as the "stereo field", or a "sound field". However, conventional two speaker systems can only produce a stereo field of 20 to 30 degrees (or so), This is because the field is created between the speakers, and if they are placed more than 30 degrees (or so) apart the central images become progressively bloated and diffuse.
Whilst AV systems are primarily designed for recordings mixed for multi-channel systems, not conventional stereo. They do try to accommodate stereo recordings, and Dolby Pro Logic II can even derive an AV 5.1 mix from a stereo source. However, the latter is the opposite of what I'm seeking to achieve.
I use an AV system as a convenient and inexpensive donor of hardware to reconfigure for the reproduction of stereo recordings. My priority is to widen the reproduction of the stereo field, by feeding each of the two input channels to two or three speakers without mixing, cross-feeding or manipulating the stereo source (other than the setting of the volume levels fed to individual speakers). This rules out the use of a center speaker, and the single rear speaker of an AV 6.1 system.
I have developed an analogue unit that can vary the presentation of a stereo source from 1 to 3 times the speaker-to-speaker spacing, whilst maintaining the overall volume within 1dB. Furthermore, the unit is not only passive, it is purely resistive, and so has no "sound" of its own to colour the presentation.
Sounds too good to be true? I have a system set up and I'd love to demonstrate it to anyone willing to listen. Well, when Covid restrictions allow... I'm also setting up an area on my blog giving instructions on how to build a simple fixed-setting unit, and even how to set up a system without a unit, just using phono "Y" cables. I'll give the link when it is available, assuming that does not contradict any site rules?
Whilst AV systems are primarily designed for recordings mixed for multi-channel systems, not conventional stereo. They do try to accommodate stereo recordings, and Dolby Pro Logic II can even derive an AV 5.1 mix from a stereo source. However, the latter is the opposite of what I'm seeking to achieve.
I use an AV system as a convenient and inexpensive donor of hardware to reconfigure for the reproduction of stereo recordings. My priority is to widen the reproduction of the stereo field, by feeding each of the two input channels to two or three speakers without mixing, cross-feeding or manipulating the stereo source (other than the setting of the volume levels fed to individual speakers). This rules out the use of a center speaker, and the single rear speaker of an AV 6.1 system.
I have developed an analogue unit that can vary the presentation of a stereo source from 1 to 3 times the speaker-to-speaker spacing, whilst maintaining the overall volume within 1dB. Furthermore, the unit is not only passive, it is purely resistive, and so has no "sound" of its own to colour the presentation.
Sounds too good to be true? I have a system set up and I'd love to demonstrate it to anyone willing to listen. Well, when Covid restrictions allow... I'm also setting up an area on my blog giving instructions on how to build a simple fixed-setting unit, and even how to set up a system without a unit, just using phono "Y" cables. I'll give the link when it is available, assuming that does not contradict any site rules?
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Not to detract from your efforts here, this sounds like you have a problem with your speakers, or their application.
I too suspect imaging problems. For decades I made recordings with a solid 60 degrees record and playback.
Is OK to give a link to my "Hurst Audio" site? I set this up hoping to be able to commercialise the units, but it is at present purely informative. No sales info.
it is fine to do that 🙂(If/when it does go commercial (as in asking for money for the product/services) then that is when we would move the thread to the commercial area of the site)
This Hurst Audio UK link gives basic info. on how to build a simple fixed-setting unit, and how to set up an AV amp with just phono "Y" cables. I have spreadsheets that give the detailed designs of a range of units, but these are not particularly easy to read or use. I'm also cautious about giving that much away. I've spent many months refining the designs to eliminate the insertion loss, simplify the designs, and select the optimum component values etc... Anyway, I hope this helps.
Thanks for the comment. I have a range of equipment that I use for test purposes:
Media: CDs ripped to WAV files stored on Toshiba, Dell and Samsung laptops, replayed via internal and external DACs including a Cyrus Soundkey.
Budget system:
TEAC AG-15D Home Cinema 7.1 amp,
Microlab FC330 satellites (6 of),
JPW SB1 subwoofer powered by a Pertors C236 amp.
Vintage goodies:
Kenwood C-V350 pre and M-A300 power amp 5.1 combo.
Wharfedale Diamond I's (4 of).
Wharfedale PPS-1S Subwoofer.
Easy Listening:
Pre-amp, Rotel RKB-650 6.0 power amp.
Ariston MSX-07 micro monitors (6 of).
Listening room 3.6m x 2.25m
It seems unlikely to me that the speakers are at fault. However the listening room is small, and this could affect my perceptions. Ideally I would like to have a small and a large listening room, but the absence of a large room does not, of itself, invalidate the experience of listening in a small room. what I hear is what I hear.
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I may have not expressed myself clearly. I meant to suggest that, yes, you can produce a 60 degree sound field with just a pair of speakers, and you might be perfectly happy with it, but did you ever compare it to the same recording replayed by the same speakers placed 30 degrees apart?
One of my designs for a six channel system allows you to feed the stereo source to each one of the three pairs of speakers individually. I assure you there is a difference.
Thanks for the link. This seems straight forward and well explained. 
With my Yamaha 7.1 receiver the analog multi-channel inputs could be used with splitter Y cords. The levels between the speakers can be set inside the Yamaha. I could even do all the routing and levels on the computer and send 4 or 6 channels over HDMI.
A very long time ago I ran audio for a show where the source was 2 channel tape fed to a 24 channel Soundcraft mixing desk. The inputs where used as veriable outputs allowing me (by hand) to send the audio to any one or many of the 30 speakers that surrounded the audience. In this case the goal was to move and shape the sound in real time.
With my Yamaha 7.1 receiver the analog multi-channel inputs could be used with splitter Y cords. The levels between the speakers can be set inside the Yamaha. I could even do all the routing and levels on the computer and send 4 or 6 channels over HDMI.A very long time ago I ran audio for a show where the source was 2 channel tape fed to a 24 channel Soundcraft mixing desk. The inputs where used as veriable outputs allowing me (by hand) to send the audio to any one or many of the 30 speakers that surrounded the audience. In this case the goal was to move and shape the sound in real time.
way back in the early 70's I played with passive 4 channel sound from a regular stereo recording. I cant remember all the details, I think it was L-R and R-L and a couple of resistors for the rear channels. Some records had a great front to back or diagonal movement of sound, others had little or no effect.
There certainly is! I'm listening to a 6 speaker stereo setup right now and the effect is very obvious but not overwhelming. My setup is just thrown together with 3 very different pairs of speaker and yet it works well.
I have done the routing and levels in software (JRiver) and not passively, but it's the same thing. Center image is strong, of course, because the mains are close together. The images spreads out across the speaker array nicely, with certain sounds coming from far left or far right, and some in between. I didn't have enough room to spread the array as far as it should be so I have cheated by delaying the outside pairs thus pushing them about 6 feet farther apart. No delay on centers, 2.5ms on next pair, 5ms on outside pair. You have to be careful with that, as I found it can cancel bass. Positioning needs to be played with.
I can easily bring the center pair up and down in volume which has the effect you would expect. It's easy to tune by ear.
With a set of 6 identical speakers this could be very satisfying. I can imagine endless tweaking, of course, but the effect is very nice, good width, image and envelopment.
Thanks for this comment. I remember the arrangement you describe well. Please do not confuse what I am suggesting with that. To repeat, I propose no mixing, cross feeding or manipulation of the source recording other than setting the volume levels of individual channels.
Thank you. I hope that you will soon be able to hear the system with matching speakers, and that it lives up to your anticipation.
It worked surprisingly well with a random assortment of speakers, so identical speakers across should be really great. I hope that other people try it.
What do you feel about spacing and angles?
I hope that other people try it.What do you feel about spacing and angles?
No matrix, no center channel. Just same signal left and right with the inside speakers a little louder.
@KSTR
Thank you for the link. I have only read the abstract, but it is clear that, whilst he was addressing a similar problem, Michael Gurzon's solution was very different from my proposal. In particular he envisaged applying a frequency dependent phase shift be applied to the source and the use of three speakers. I explicitly rule out the manipulation of the source, and the use of odd numbers of speakers.
Thank you for the link. I have only read the abstract, but it is clear that, whilst he was addressing a similar problem, Michael Gurzon's solution was very different from my proposal. In particular he envisaged applying a frequency dependent phase shift be applied to the source and the use of three speakers. I explicitly rule out the manipulation of the source, and the use of odd numbers of speakers.
I suggest that the speakers are equally spaced in a straight line. I suggest you follow the manufacturers recommendations about angling the speakers, though I suspect that most speakers should be "toe in" to face the listening position. I have considered other arrangements, and I have modelled them in a spreadsheet. One arrangement that I do NOT recommend is the placement of the speakers in an arc equidistant from the listening position.
@Pano
You said that you used delays to simulate a wider spacing of the speaker. There are a couple of alternatives you may like to try:
- Bring the outer pair forwards, to allow the inner 4 speakers to be spaced out a little, whilst the speaker-to-speaker distance is the same.
- Use four speakers instead of six.
You said that you used delays to simulate a wider spacing of the speaker. There are a couple of alternatives you may like to try:
- Bring the outer pair forwards, to allow the inner 4 speakers to be spaced out a little, whilst the speaker-to-speaker distance is the same.
- Use four speakers instead of six.